Weak Immune system plus Autoimmune disease. What do I do? My doctors are useless.

26M, 5'9 135lbs. Non smoker. Current conditions: Psoriatic Arthritis. Current meds: Hydroxyzine & Cefdinir. I am posting this here because I have nowhere left to turn. The medical system has pretty much failed me aside from giving me temporary solutions. I have had psoriatic arthritis for 5 years, been on biologics for a while, but they have been working less and less. When I start my next one soon that will be my 4th medication. My diet has been pretty good, mostly meat, eggs, fruit, vegetables. I got covid in January this year and thats when everything went downhill. I've had long lasting symptoms for 8 months: Shortness of breath, neurological problems, tingling in hands, brain fog, chest pain, severe fatigue, and the worst of which has been at least 1 new infection every month. Before this, even with my immune-dampening medication, I never got sick. But covid did something drastic to my immune system.

I ended up seeing an immunologist who told me my immune system is "fine". I have high levels of IgG4 and low IgG3. This is clearly abnormal but I guess he doesnt know how to make sense of it. So I am not given a diagnosis but I know that my immune system has been weaked somehow. Which leaves me to do what I have done plenty of times before when my doctors have failed me, is try to figure it out on my own. Vitamin D3, K2 and Zinc clearly aren't doing enough since I have been taking plenty of that for a while. I could try vitamin C but I dont know how much that will move the needle for my circumstances. I need some really effective supplement recommendations. I just got colostrum so I am trying that now. But I have heard you should not take supplements like echinacea if you have autoimmune disease because they can stimulate the immune system. But I feel like I have to take these because these infections are the main priority in terms of issues I need to address. I need all the help I can get here, I am overwhelmed with stress and anxiety.