Hi Uncle John, I'm not a Doctor but a former Nurse. Many pain conditions can be caused by inflammation, usually caused by an earlier injury you might have had or from some chronic disease. Trying to list those potential diseases here would be impossible, but you should be able to find much more online. I would write down all your symptoms such as cramps, a numb constant pain, tingling sensation etc. and see what many of the medical sites say.
Now... they might give you an "idea" of what the medical issue is, however I still highly recommend you see your Doctor and have him/her evaluate you and run the required tests if needed. Don't think of health care as a "waste of money", it is YOUR life. It could be something minor that an anti-inflammatory medication will fix, however it could also be something very serious which if caught early enough can be treated - now!
Please go to your Doctor very soon and talk to him or her about it!