I have severe pain below my second toe. It was diagnosed as gout as my uric acid was at 420. I also have crackly knees and tennis elbow. Could they be related?

Normal Uric acid. Levels in a female are 2.4 - 6.0, so I am not sure what you mean by 420? How was the diagnosis of gout made? Was the region aspirated? Gout is also monarticular meaning it usually occurs at one joint. Crackly knees and tennis elbow have nothing to do with gout. I question the diagnosis given.
I doubt gout. Gout is characterized by intense pain and swelling. It is extremely unusual in a premenopausal female. Get another opinion.
Possibly. You have symptoms which could be serious and should see your physician. He/she will listen to you, do a physical examinarion, run some tests, and let you know what's going on.