Pain in sternum and just above abdomen.

I having sternum pain for more than 2 years. It was severe if I crack any nut in sternum. But now I'm unable do so and the pain it manageable. But still it appears quite frequently May once in 2 days and goes off. Having pain at the bottom of sternum or just above the upper abdomen. I'm having this pain for about 3 months. I had stomach ache and digestion difficulties. I was diagnosed with gastric ulcer and doctor asked to take medicine early morning for 3 weeks. Now I feel better when it comes to ulcer or stomach pain. But pain below sternum still continues and i can feel the pain even if I press that area. I had joint pains before a month in my hands after waking up. My orthopaedic doc suspected it to be arthritis but the blood result was negative. The medicine which he gave didn't work well but I started having pure cow milk in the morning and the pain is gone. Having occasional knee pain even. Which goes off on its own. Damn afraid to have all these problem at this age.