My cat just gave birth to 4 beautiful kittens but after her labor she started breathing rapidly. It has been 8 hours since, and she is still breathing rapidly and now she is also opening her mouth while sticking her tongue out. she already ate twice and drank lots of water but since her labor she hasn't done the restroom, I believe she is straining and now im very worried for her. what can be happening with her? what can I do?

Rapid breathing (tachypnea) is a respiratory disorder characterised by abnormal breathing that is rapid and shallow.  It is caused by a reduced level of oxygen, mechanical disorders (where the lungs aren’t able to expand as they should, usually due to a build-up of fluid in or around the lungs), and physiological disorders in which the cat’s respiratory centre in the brain is over stimulated.