I Have 2 Golf Ball Sized Lumps In The Mid

I have 2 golf ball sized lumps in the mid region of my left thigh. They appear to be fixed in position and do not move when I press them. I have had the lumps for a couple of years but have never had them checked. I play football and recently have started running, over the last couple of years I sometimes feel fatigue and ache in the area. However, over the last few weeks I have been experiencing pain in the area when running. This pain or fatigue is not mirrored on the right thigh. What do you think it is?

Regards,

James