Is it too much of a supplement for an 18 months old?

Hi mummies. May I ask for your opinions? My son has always been sick. When I said always, I mean, all the time. Our trips to the doctor are so frequent that one time, the nurses and doctor asked, 'is you again?' 'what this time?' 🥺 his sickness is always cough, flu, fever, diarrhea and recently, he was admitted to the hospital due to pneumonia and influenza A (he was already vaccinated for both of these). All along, he has been on prebiotic and probiotics daily. Recently, a pharmacist friend recommended tiger milk mushroom and elderberry (with vit C and zinc). Out of desperation just to try everything so he doesn't always get sick, I got those for my son. So for a few days now, he's on 3 kinds of supplements. Morning - prebiotic and probiotics After dinner - the elderberry syrup (contains vit C and zinc) Before sleep - tiger milk mushroom But now, I am doubting myself, and I'm very concerned. Am I feeding him too much supplement? #firsttimemom