Suture material

Question
Hi, I took my dog to spay about 2 months ago. She was completely fine after the surgery, the wound healing nicely until about 1week later, the scar area started to become red and swollen with yellow pus coming out. I took her to the vet again. The vet said she is probably allergic to the suture material (vicryl) and gave some antibiotics, lotion and habitane. She then started to heal. At the last check up, the vet said she can stop the medicine and the wound should be healed now, while the suture material will take another few months to completely dissolve. However, just a few days after my dog stopped the medicine, she started to have a cyst like lump near the wound area. It was red at first, now became black. Not sure if that is black pus?

Of course I should take her back to the vet. But I am so tired of bringing her back and nothing seems to solve the problem. I appreciate if I can get a second opinion.

Answer
This is most likely a foreign body reaction to the suture.  It may also be infected.  The vet may need to culture the pus in the wound to see if there is a bacterial infection.  The vicryl should be removed and if it needs to be sutured again, then they should use something like stainless steel wire, which is not reactive.