Supplement combination/effectiveness

Ergomax brand PEA was working so well after 9 weeks of 1200 mg. Per day, thought I was 'cured'. Pain and burning was rare and brief! Then...it comes back. Who would one go to in order to find out if supplements are cancelling each other, overkill in combination taken etc.? I take alpha lipoic acid in the R-ala form, acetyl L carnitine, turmeric and B12. Continuing with PEA since I stocked up! Medical doctors? doubt it, health food stores? Probably sell you more stuff! How do you find a chemist or biologist perhaps? Thanks for any advice.