Sudden dizziness symptoms and conditions

I am 34 years old. Back in 1985 I had most of my thyroid removed, due to a tumor attached to it. Since I was 10 until my late 20s, I was on Synthroid. By age 19 I had 3 knee surgeries to remove arthritis. I have suffered most of my life with joint pains, dry skin, weight that is like a roller coaster, and being tired most of the time. In my 20s I was put on Levoxyl. I has been on Levoxyl for several years now. Since being on Levoxyl I have been fighting anxiety, racing heart, joint pain in fingers and ankles, sudden dizziness to the point where i have to sit or pass-out. I feel like I'm 80 and not 34. After reading this site I am printing all this out and taking it to my doctor. No telling how much damage has been done after all these years.