Just lost third gear

Ok, I just lost third gear, i mean completely, no grinding, no previous indications of issues, no grinding no problems prior to this. I shifted at about 5 to 5200 so was not maxing it out by any means. I Have all the other gears 1,2,4,5,R no grinding in any of them. when I go int 3rd the feeling is as smooth as usual with no grind, but when I press the gas it is as if I am in neutral. I thought i blew the syncros but while driving it at low speeds i kind of slipped the clutch while going into 3rd and got some grind which tells me the syncros are still there. but if I shift nornmally, nothing! not a grind or stiffnress going into third gear just revs like in neutral.
Can anyone shed some light on this problem? Please? This is my DD and right now I do not need this. As soon as I calm down I will search the archives and take it to a shop. My Fiance just had a brain aneurysm 12 days ago in front of me and is still unreponsive so if you are going to preach research the archives or tell me how this has been covered, or how I should read the rules, or lecture me on driving habits, please just dont reply. I would rather have nothing than have arrogance as I am beating myself enough!

I am sorry if i seem like an ass right now but please understand my circumstances, If someone can relate to my situation and has any sugestons or knowledge please share! Could it be in the linkage?

the linkage would effect all gears, not just third. sounds like an internal transmission issue.

First thanks for the response, second I appologize for the tone of my OP! I actually tried to delete it but couldnt figure out how. Have just been through a lot this last week and did not need this. But it is what it is.
I am sure thats what it is, just odd that I did not notice any signs previous to this. I know Mark will be dissapointed in me since he built such a nice car. I have a fresh built tranny with less than 100 miles on it in my garage so maybe that will help. Thanks again