What do I have? Oral thrush or something else?

it all started a year ago when I took a slimming pill. I started to feel weird symptoms after few days, including tightening of the throat, dry mouth, insomnia, etc.
After the first week, the drying of the mouth seemed a LOT. I continued but after hitting the second week, I felt my mouth burning!!!!!!!!! I went to see what was it and saw it was cracked, red, and swollen, and white coated. I stopped the pills then went to see a doc and told me I had GERD. Took treatment but turned out wasnt GERD. Now a year later I still have this tongue issue I dont know what could be. Can someone help me. I feel so miserable.