My mother 48yo suffers from knee joint pain, even difficult for her to stand, most of medical tests were ok, no medications proved useful:( please suggest?

Rheumatologist: Which tests were not ok? A good rheumatologist should be able to sort out whether her problem is an inflammatory condition (e.g. Rheumatoid arthritis) vs. Osteoarthritis. The former can require weekly injections to alleviate and take other medications like Methotrexate that take months to work. Steroid injections can help as well. If osteoarthritis and degeneration/symptoms bad total knee.

Knee Pain: If she suffers knee pain and all the tests including xrays and MRI of knees are normal then the assumption is that her pain located in her knees is referred from another source such as her back, neck or hips. Meds may not be helpful if directed at the symptoms and not a specific diagnosis. She is very young to not be able to stand due to her pain. Would not stop looking for the problem at this.

Another opinion: Knee pain can be due to several causes and in some the lab tests and x rays can be normal. Have her evaluated by a rheumatologist or orthopedist.