Pain in Lower Abs

Hey guys, This seems like an unlikely injury to have, but anyway…

2 weeks ago after doing 5 sets of decline sit ups at the end of my workout, i felt great…

few days later, some pretty bad DOMS (sitting out of bed was a real struggle, but hey,
i don’t bother insolating my abs, i figure squats hit them hard enough), so a week later
i go to hit my abs again, doing pull ups - the lower part of my abs on the right side are aching …just from a few pull ups…

sit ups - forget about it

a week later, the same problem it still hurts too much to do any ab isolation. it shouldn’t take
this long for the muscle group to recover right?
any suggestions?
cheers