Flare = return of symptoms. Sore throat and swollen glands are not typical symptoms of mctd but muscle and joint soreness definitely are. Treatment for mctd is usually LONG TERM prednisone and also prednisone sparing meds like imuran and methotrexate to suppress your immune system. A single shot or a short term treatment will only brieflly, if at all, suppress your immune system. I have been on pred and imuran for over 4 years although the doses are now minimal. I was on 60mg of pred initially and after 9 months still on 25mg and 150mg of imuran. Short term, one time treatments don't work for a disease like mctd.
Is your doctor a rheumy? Is he experienced in treating AI diseases? I suggest that you find another, experienced doctor. If he has treated lupus patients he will know how to treat mctd. It is unusual to give a single shot for mctd and expect results. Don't wait since your disease is symptomatic and might get worse.
MCTD (lupus, scleroderma, polymyositis). Diagnosed 2005. Kidney, liver, GI tract, dysphagia, raynauds, Barretts esophagus, quadriplegic in 2005. Recovered and now active in skiing, tai, chi, hiking, golf. Meds: prednisone 2.5mg, imuran 25mg, amlodipine, benazapril, omeprazole, potassium, folic acid, vitamins, maxide and various supplements and vitamins.
Remain optimistic and you can overcome the odds.