I was rightly or wrongly diagnosed with tendonitis about 1 month ago, it got about 90% better but then last week it became worse and now the same feeling is in my 'elbow pit' (as in the inside). Just today my 'knee pits' also seem affected by the same thing. I get tingling when i keep these parts of my body still, when i subject them to force they hurt more than would be considered normal. It feels like all the tendons in these places have gone hard but one doctor (who i am due to see tomorrow) said that they should be hard and that he doesn't know why 'it' has 'spread' and wants a blood sample. I am 18 and male, if that makes a difference. I would like to know what is wrong with me.