Hi Marzy,
I had a touch of OHSS which only appeared after ET. Also I had severe cramps and spasms in my abdomen. The clinic said it sounded as if my uterus was in spasm.
This was bad in the first week of the 2ww and then improved.
If you experience OHSS symptoms such as problems breathing and nausea/vomiting give the clinic a ring and ask their advice.
Hope that it gets better soon.
With warmest regards,