Pregnancy Possibilities or something more serious?

Ok here is the low down on it all:

I got my period on 7/2 and it lasted for until 7/5. I had unprotected sex with my fiance on 7/6 and he did not withdraw.

On 7/16 I started having light cramps, small waves of nausea and spotting.
On 7/17 the spotting stopped but I had no appetite due to the continued nausea.
On 7/18 the spotting resumed accompanied by light cramping, back pain, and nausea.
On 7/19 the spotting, cramping, back pain continues. Sometimes the cramping and back pain is worse than usual but not unbearable.
On 7/21 the spotting has stopped and I'm haven't experienced any cramping or back pain except for when I lie down. Nausea in the A.M. and hungry in P.M even though I feel bloated.

Sleeping on my side now is too uncomfortable because of the full feeling in my stomach so unless I sleep with a body pillow I must sleep on my back with a pillow underneath.

7/22 I had terrible, painful constipation in the A.M.

Also experiencing grinding teeth, heartburn, bloat, fatigue, adversion to eating, swelling, pain in left ear, irritated sinuses.

I'm wondering if I am actually pregnant and if not, I'm worried it may be something serious.

Thanks for all your help!

TLC