Pregnancy Test............. HELP?

[Natalie N]

I took a prego test about 2-3 weeks ago and it said neg...I forgot about it n threw it in my drawer...I haven't had my period since June 9th and thought it was pretty weird and have been worrying about it for some time now....I don't think I am based on the fact that all I have is a couple missed periods. Also I worked out for a couple weeks straight which might have caused me to miss one. Anyways...I took a test again today and it said neg. so I thought it would be alright if I started the pill today, after taking the pill i felt sick and tummy was pretty girgly...I thought it may be because I haven' eaten all day. When I get home I was looking for a remote and found the prego test from 2-3 weeks ago and it now says positive...Can that actually happen?? The test I took earlier today still says neg...The test says that after 10 minutes it is invalid but I dont see how a neg test can go to pos. The air does not carry HCG hormone....HELP