My DD did the same at 5months, started going crazy at night ( she was waking hourly tho).

MCHN encouraged me to start solids due to poor weight gains, which we did at 5.5 months, made no difference to a) the night wakings or b) the weight gain, so don't expect a miracle is what I am trying to say! I don't really regret starting then but there's no reason she really needed it either.

Is she going through a wonder week? DD always has awful naps and night sleeps during this, then it magically fixes itself again.