What causes a hard, tender, and warm lump near the anus?

Hi doctor,

I am in real pain for the past 9 months and my doctor is clueless after several visits. After a period of 38.6 weeks in latent labor, I had a vacuum-assisted vaginal delivery (first baby). No ultrasound was done on the very day of admission. With crowning left mediolateral episiotomy was given. An extension of 0.5 inches up to the anal sphincter was given and sutured. I gave birth to 7.9 lbs baby girl. After 2-3 days in the hospital, I kept complaining about excessive pain and burning in that suture compared to others. I was told that it was normal. After a month I could barely sit and feed my baby. In the follow-up, the doctor told me it was normal and healing. After 2 months it worsened again and I could feel a hard lump on the left side below my vagina and near the anus. It has been 9 months now after my delivery and every 4th day or once a week I get the lump tender, warm, and hard in between my vagina and anus, along with the discharge of pus or light-colored blood which is immensely painful. It keeps coming back always. I am getting weaker day by day. Mild fever, stiffness in legs, body ache, inability to move and sit when the pus forms until it discharges from a hole that has been there always. The same hole closes each time after discharge. Which doctor should I visit? Please help me urgently. What can this be?