I am almost always tired. I sleep till 2 or3 in the afternoon and sometimes won't wake up to an alarm.

when i finally crawl out of bed i have NO energy and feel like i could go to sleep again and sleep for days..

i am constantly yawning.

could it be CFS and should i go to the doctor

Yes, you should go to the doctor if you are not feeling well, and like yourself.
Please let us know how it goes.
Tawny