Had hysterectomy 5 wks. Seroma drained 1 wk ago. Groin/abdomen/upper leg burning pain returned but worsening. Doc felt it might be nerve issue too??

Abdominal pain. You did not note why you had the hysterectomy. It could be related to that if ovarian or uterine mass issue. It could be nerve pain but also could be recurrent seroma or infected seroma or adhesions (scarring that occurs post op). Consider repeat CT/ultrasound.Discuss with your doctor/ER/urgent care.