Could Nausea Be The Symptom Of Concussion?

My 81yr old mother had a fall in the kitchen yesterday after slipping on a throw rug with no tread left. she hit the back of her head on the front of the dishwasher. Immediately after we got her up, she has been complaining of nausea. There is no bump or visual redness on her head but only sore to the touch. My question is, could she still have a slight concussion even with immediate nausea? This is what s worrying me today as it s been more than 24hrs since the fall, she is sore today and a weak, resting today for the most part.