Hi there I am going to be dead honest with you here, I have never used Kusuri or Fluke solve so I am afraid I could not make a recommendation on the uses of these products. I kept most of my discus while I was in Germany so used mostly products that were available in Germany like Flubenol or Flubendazole.
When you receive the products either ask the seller a question or see if the guidance instructions on the packet give any indication on whether the two products can be used together. My gut reaction is not to use both products together.
Getting back to the point in question, all is not lost remember I said you need to try a process of elimination to narrow down the possibilities, well let's look at the Fluke Solve first. The Fluke solve is for Gill Flukes which affect the gills and prevent the fish from breathing properly. If you see the mouth opening and closing more than 60 to 80 times per minute that would indicate that they are having to pump more water through their gills to get the oxygen they need. It is a bit like us when we run, we start to breath quicker to get more oxygen. If the discus fish has gill flukes this reduces the efficiency of the gills to transfer oxygen so they breath quicker to try and compensate. Some discus will start breathing to a rate of 120 to 180 per minute which is really bad. This stresses the fish out and they stop eating and the situation goes down hill from there.
Secondly, the Kusuri product is a worming treatment for removing parasitic worm infestations of the digestive tract. Oddly enough a lot of discus carry these worms but they never become a problem until the fish get stressed and then the symptoms really start to take over. So you have to observe the fish, the other fish in the tank with them, the water parameters, CO2, temperature etc and carry out a few measures but not too many or you will never know what it was you did that cured them.
Raising the temperature is a good start, switch off or reduce your CO2 injection by about 50%. There is some evidence that people have experience problems with CO2 and discus especially if they come from a none CO2 tank to a CO2 tank without a period of gradual acclimatisation. In my planted discus tanks I switched off all the CO2 for a week or two until there was virtually zero CO2 and then started adding it gradually until the fish got used to it. Remember the CO2 helps the plants to photosynthesize and give off oxygen which is a good thing, as long as you don't overdose it.
This is what I would do if I were in your position, rather than bung whichever product you decide to go with first into the tank, try the bathing method. A small 10 to 15 litre container with the respective amount of treatment for that quantity of water, use your tank water not fresh water, 29 to 30 degrees if possible, no filtration but a gentle aeration using an air pump and stone, remove the fish from the tank as carefully and gently as possible and place in the container out of bright light but not pitch black. Make sure there is a lid on the container otherwise the discus could jump out if it gets over stressed, I have used large Tupperware containers in the past which means that you can observe the fish but it can't see you. If possible and the fish does not show signs of severe stress like floating upside down or lying permanently on its side, try keeping the discus in the container for anywhere up to an hour but at least 20 minutes. Observe the fish every few minutes to check for changes, make sure you do not overdose whichever medication you choose to use first. My bet is you will go for the worm treatment first.
There would be no harm in treating both fish at the same time, just might need a bigger container.
My only other query is your fish list, everything on the list looks fine to me except the Botias. If you mean Clown loaches, the orange and black ones, these are notoriously boisterous and like to rummage around everywhere looking for food in the substrate, which is what the discus like to do except a lot slower. The Botias might be disturbing the Discus eating? Take a look at this link for how big these things can grow...
http://www.ivanov.ch/images/-poissons/c ... ch_big.jpg
Other points of reference are the links posted below. Don't just take my advice, have a look at what is out there and maybe get involved in a specific Discus Web forum such as BIDKA, or UK Discus Association.
for reference...
http://forum.simplydiscus.com//index...d=7094;start=0
http://forum.simplydiscus.com//index...d=8162;start=0
http://forum.simplydiscus.com//index...=7526;start=15
http://forum.simplydiscus.com//index...d=9616;start=0
http://forum.simplydiscus.com//index.ph ... 94;start=0
Good luck and let me know how you are getting on.
Cheers,
Steve