HELP!! constipated baby

My son is 6 months old and I'm pretty sure bananas made him constipated...he pushed for a while and only a tiny bit came out. What can I give him so he isn't constipated anymore? I've read one ounce water one ounce apple juice... is that true? Or any other remedies. I'm a ftm and he's never been constipated and I'm freaking out. His doctor doesn't open for another 2 hours. 😭 someone help