I'm 4 weeks 5 days pregnant and about 2 hours ago I started having a feeling like I am going to start my period.  It's not really a "crampy" feeling, it's more like a moderate ache in my lower abdomen and lower back.  It's making me a little nauseous/diarrhea (Sorry, TMI) feeling.  
Is this normal?  Should I call my doctor?  Thank you for any help you can offer! 
*Edit- I had my 2nd beta done today and my number was 485, which had doubled from beta 1.  
                 
                3/09 off BCP
TTC 6/09
DX PCOS 9/09, endometriosis, bicornuate uterus
DH- All #'s are above normal!
1500 mg Metformin
6 rounds of Clomid + HCG trigger- All BFN
8/10 IUI #1 Gonal F + Ovidrel BFN
9/10 On a much needed break
10/10 Laparoscopy
11/10- 6/11 IUI #2-4 Gonal F, Ovidrel, and progesterone, produced 4-8 follies each cycle, all BFN
8/11 IVF #1 R-20, M-17, F W/ICSI 2 

 3dt of a 4 cell and 7 cell BFP!!!!
BETA #1 115, #2 488, #3 2900
-SAIFAW- PAIFAW-

Re: 4wk5d Worried!
Because we're fancy like that.
DH became a double above knee amputee with traumatic brain injury (TBI) - July 2009
TTC - August 2009 DX: Severe MFI & TF due to TBI
DH SA 0 count, started clomid therapy - November 2010
DH SA 0 count, increased clomid dosage - January 2011
DH SA 75 million with 60% motility!! - May 2011
IVF with ICSI ONLY OPTION - May 2011
3dt of 2 Grade A 8&7 cell embryos May 19, 2011
+HPT May 30 2011 -- Memorial Day!
Beta #1 = 34 Beta #2 = 101.8 Beta #3 = 603!
Expecting beautiful Eden Grace February 7, 2012!
I don't believe that God ever tells us "no". he has three options. Yes, not right now, or I have something better in mind. We just have to wait & see.
7lbs 13oz 20 inches long