Sorry it has taken so long to respond. By 0.6mg i assume you actually meant 0.6mg/kg. For a 75kg person this is 45mg. 0.6mg is a very small dose that will not be effective. My doc uses 0.6mg/kg, once weekly.
I tried ivermectin alone for several weeks (0.6mg/kg once weekly) and did not find it effective. My symptoms slowly returned. I hear that some people do find ivermectin alone effective, but I dont think anyone can confirm cure from ivermectin alone.
In my experience, ivermectin must be combined with another drug. And I do not think that any single drug can cure PR. Combinations are necessary. This isnt so surprising because there are other protozoal diseases that require combination therapy, like malaria and Chagas disease.
If your doc is being an idiot and giving you a hard time, I suggest you simply buy horse dewormer, like this product:
Veterinary medicines are exactly the same as medicines labeled for human use. They are just a lot cheaper, typically. You will need a scale to dose this accurately, since its a paste. its 1.87% so calculate the amount needed for 0.6mg/kg body weight.
Ivermectin can cause some neurological side effects like mild hallucinations and visual disturbances. This effect is minimixed by taking it as a single large dose, instead of multiple doses over a few days. It takes time for the ivermectin to penetrate the brain, so taking it as a single large dose minimizes this effect.
Ivermectin is fat-soluble, so always take it with food. This is an advantage of getting the horse paste. Its already dissolved in oil, so I think it provides better absorption than the pills. My personal experience with both is that the paste is absorbed better and works better.
Below are some papers on ivermectin-toxicity and such.