Medical Advise On Consumption Of Increased Dose Of Zoloft

hi, im 17, 163cm and weigh 51kg. i ve never had many health problems, but i do take 50mg of zoloft every morning and have been for about 8 months, once i had some bad side effects when i increased dosage to 100mg but it was just nausea and disorientation nothing like this. after that happened i went back to 50mg and i ve had no other side effects since. (this was a few months ago) im not sure if this issue is related to my medication or not, but few days ago i woke up and my right arm pit was really sore. it felt like it was bruised but when i looked at it there was no lump or anything. it just really hurts especially when i press on it, kinda of like when you press on a bruise but more of a sharp pain. also i ve had a thing that looks like a few bites inbetween my middle finger and the other one next to my pinkie on my right hand i scratch it cause its reeally itchy, but it swells and gets really sore, its seeping a bit with clear liquid and looks raw and the skin is crusty, do you know what either or these things could be? should i go and see my doctor? thankyou for reading this :)