Uy mamsh, 4 months pa lang post-CS kaya normal pa ang fluctuations ng body mo, ang CS ay major surgery talaga, kaya medyo matagal ang recovery ng katawan at sistema ng digestion mo, lalo na kung maselan ka before pa lang! About sa bagong allergy sa seafood, maraming nanay friends ko ang nag-experience nito after pregnancy, parang nag-reset ang immune system sometimes, pero yung frequent nausea, hindi matunaw, and the sudden weakness, dapat puntahan mo na ng doctor para ma-check kung may hormonal imbalance o deficiency ka (iron levels, vitamin D, all that), hindi lang basta side effect ng CS yan. Yung mainit ulo mo every gulo is also something to mention sa doctor, could be stress, could be something else, pero worth checking out talaga with your OB o family doctor, mamsh, para sure ka lang. Kapit lang, pag-aga pa lang ito ng recovery mo, pero need mo ng proper support from professionals!