"Left little finger pain"

About 5 months ago, I realized that my little finger around the main joint area was swellen and was also red and painful. I associated it to working in the backyard when putting some stones in ground to build a pathway and it was cold and raining and although I had gloves on, my hands got very cold and I put a lot pressure on my hands.

Since then I have been experiencing pain, itchiness and sometimes burning sensation which comes and goes after I try to bend my left little finger from the main joint area.

Still the finger hurts. I have pain when try bending it and can not fully bend it. Had a cast on for a couple of month ( picked up from pharmacy) and swelling got reduced, but an orthopedic doctor told me to remove it and go physiotherapy since the power of my hand depends on little finger and he was concerned that the cast may limit mobility.

I removed cast for a day and tried to bend it slowly and did my normal work and it got worse again. Ichy, a bit of burning, pain and it turns a bit red/ purple (bruised). It also gets a bit warm in the area and swelling worsen (should  be inflamation.) Keeping it warm helps. Cold air or water make it worse.

He had prescribed a cream to releive the inflammation. X-ray shows no fracture and ultrasound shows the following:

"Evidence of hypoechoic area at dorsal extending from PIP level distally- Synovial thickening or focal soft tissue thickening."

5 months is a long time - Can you help? Any idea would be appreciated.