Raising the temps up to that range typically speeds up the cycle of the parasite. 86 is right on the border of preventing the parasite from dividing once it falls off the host and forms a capsule.
When using heat to treat Ich, it's pretty typical to see a sudden increase in visible symptoms as you are speeding the life cycle up. For example...if you gradually raised the temp, the parasite could have fallen off the host, divided ALOT, then reinfected your fish before the temps ever got up to 86. At this point, what you should expect (hope) to see is those spots disappear, and then the lack of a rebound. Suffice to say, it will take more than 3 days to kill the Ich with heat. I'd keep your temps up for at least 2 weeks.
If you don't have any heat-sensitive fish, try raising the temps up just a little higher. IIRC, anything above 88 degrees will actually kill the parasite in the free-swimming stage.
If you don't have any sensitive fish, you could also try adding aquarium salt to the tank at a lower dose (1/2 tsp per gallon is what I've used in the past). It will encourage the fish to develop their slime coat, which assists them in healing and makes them less susceptible to the parasite attaching.
To be honest, I wouldn't be hesitant in using Rid Ich+...you may risk staining some things in the tank, but I only noticed staining on suction cups and the line for my airstone when I treated my tank. I used a 1/2 dose in my planted tank in combination with heat (86 degrees) and salt for 2 weeks and wiped out Ich...as far as I can tell. I have RCS and amano shrimp in that tank...and even had RCS fry do just fine during treatment. I didn't notice any loss of fauna...although a couple of my plants didn't appreciate the salt treatment too much.