How did you partner fix his problem with slow sperm if he had this issue?

My husband went to the doctor a few months ago and has some blood work done and his testosterone level was low.

His doctor said that his sperm count came back great. His doctor recommended he took three months worth of testosterone shots and then seeing what happened after that.

In the meantime his doctor ended up leaving for a little bit of time and a another doctor filled his spot.

When he went to the doctor appointment today to get his results from his last blood work she said his testosterone levels came back up to normal. But she said she was looking over his results from his sperm test and his sperm is slow. I don't know why the other doctor did not see this problem before but either way I am wanting to ask other people out there that had this issue for some feed back and what worked for them. Thanks