I stumbled on this group while looking for some answers about MCTD and am happy to be part of it.
I knew there was something going on for a long time. Over the years I got fibromyalgia, and "it's all in your head, attitude." Using recent test results, I finally did an Internet search using this info, and it looked like MCTD. I almost almost had to force my GP for a referral to a rheumatologist . He confirmed MCTD after an hour physical, review of tests, and a long discussion. He start me on Hydroxychloroquinine which had side effects and had to stop. I was dizzy before and when I was on the drug, and so it continues along with the symptoms I've had for years
It's my experience that plaquenil takes a while to work. Most of the drugs prescribed for mctd made me dizzy and always gained weight with any anti inflammatory or pain medication. Took some time but my mctd is under control with methotrexate. Scary but for me it works. Hope you find something that works for you.
Dizziness can be a sign of pulmonary arterial hypertension. Do you also have shortness of breath? Might be worth a consultation with a cardiologist. Hydroxychloriqine (Plaquenil) worked for me for many years. It's supposed to prevent the disease from getting worse and I think it did in my case. For a long time, anyway. Might be worth the side effects if you were dizzy before taking the drug anyway.
Good luck to you