Pain in a lower abdomen

[Natural Beauty]

I can identify with that! I had that when I was spinning after my first baby (9.6lb preemie) I luckily didn't have to get my plumbing put back, well, not yet anyway.
I increased my stretching (hip flexors, low back, it band) and made sure my posture was pristine. This is hard to do if your instructor is less than phenomenal.
I know half the fun of spinning is trying to kill oneself with increased tension but maybe that isn't for you quite yet. It also never hurts to get checked out by your OB to make sure there aren't any ovary issues.

[Evka]

Thanks for all responses!!

I stay hydrated, so I can exclude that.
It really can have something to do with a digestion, I sometimes have problems. Though this pain feels more gynae related and that should be OK for me - I have yearly checks and no problem reported. I'll ask about this anyway.

What is bad about this pain is that it's too late to stop / slow down when it appears... I'm trying to say that it doesn't develop, it just appears in all its 'beauty'. That is a reason why I often hold back in training, as afraid of the pain starting again. At least I know what triggers it! (the heavy hills)