My appendix ruptured and I was taken out on New Years Day but there were loads of complications so I had a further two surgeries last of which was on 16 Jan.
I was fairly physically fit, ran regularly and was proud to have a flat stomach!! Someone offered me their seat on the tube the other day thinking I was pregnant - I walk with my hand guarding my tummy! I wasn't complaining too much since I got a seat but still!
Have you seen a physio? I saw one on Friday and was advised to not do abdominal exercises for a while and she taught me how to massage my wounds - 5 in all how to reduce scar tissue forming badly. Despite my two stone weight loss the buldge isn't going and isn't going to shake for a while due to the healing and swelling underneath, I suspect the same for you.
Don't push too hard and take it easy. Sometime pain is an indications to stop! =)