Can acid reflux, lower stomach cramps, headache be preeclampsia?

Unlikely: Preeclampsia, the state before eclampsia, which is seizures in pregnancy, is diagnosed as mild or severe. Mild depends soley on bp, greater than 140/90, or not pre-existing before 20 weeks, and proteinuria. Severe needs the mild conditions, then adds either a higher bp, more protein, visual changes, and headache, with a few others, but elevated BP is required.