Hi,Dear,Welcome with your query to HCM. Studied your query in full depth of its details.Reviewed it in context of your health concerns. Based On the facts,IF another skin tag is getting formed behind current stitches in 2 days after the surgery,You mostly seem to have a slipped Venule of Cut Skin tag. Treatment- Immediately Consult a Surgeon who operated You. 1-Pressure Bandages-for 6 hrs-with 1 hrly check-If this controls the rise in the swelling,Continue antibiotics and painkillers and anti-inflammatory drugs. 2-IF the swelling continues to grow in size-Immediate surgical intervention by surgeon. A wound exploration with ligation of the Leaking Vein would fix the problem. Before doing all these things -other cause of wound infection with cellulitis would be needed by Surgeon.In that case antibiotics / with or without Surgical drainage of the wound abscess would help you. This reply would help you to plan further treatment soon with your treating doctors.Best of Luck and early recovery. Welcome any further query in this regard,which would be replied in next session. Good Day!! Dr.Savaskar M.N. Senior Surgical Specialist M.S.Genl-CVTS