My LO have not poo for two days.hes on fully formula. Is it ok?

Best if your child can poo daily, however there are some babies that poo once every 2 days. Just watch out for constipation as it can be very painful for the child when they poo (and may have traces of blood from pushing). What you can try to do is feed a little bit of water, do some "cycling" massage (https://www.youtube.com/watch?v=xqEGc7oqcXc), put a little bit of ruyi oil for the discomfort. If all fails, you can also try giving some gripe water. If your child continues to be constipated for more than 3 days, I'll suggest to bring to the PD.