My LO can't tolerate eggs or dairy in my BM. We just started baby led weaning and she had her first banana on Saturday. We gave her some more yesterday night. When we put her to bed she spit up more than usual and was waking about every 15 min-30min for the first several hours. I am not sure if it's all just a coincidence. She still spits up fairly frequently and she has been having a hard time sleeping at night. Usually she will wake up once every several hours though. I haven't really noticed any rashes and today she has been in a fine mood.
Re: a reaction?
The introduction of solids can be tough on a baby's system, especially when they've already shown signs of sensitivities like your LO has. Some babies do well with solids from the beginning, but some babies have a hard time adjusting and wind up with stomach problems as they transition to something other than BM. I wouldn't call an upset tummy a sign of an allergy just yet. When first doing solids, my ped recommended that we try them with DS during the day instead of closer to bed so that a tummy ache wouldn't keep him up. I'd say it was about a week of solids before DS's stomach adjusted and he no longer had cramps/stomach ache from eating.
As for the spitting up, does she have reflux? Is she on meds?