I went to see the doctor and he told me that my knee is as good as it is going to get after 5 months of having surgery? but still am in a lot of pain.

Agree-2nd opinion: Your surgeon's assessment may be correct; however, it is worth seeking another opinion. Many knee procedures (for example, acl reconstruction, cartilage restoration procedures) require more than 5 months of postoperative rehabilitation before maximal improvement is obtained. Find a surgeon who specializes in the type of knee procedure you had (arthroscopy vs. Fracture/trauma vs. Replacement).