Baby always sick or hurt.

My boyfriend is married but separated. We live together a hour from her. But whenever their 20 month old baby is in her care and not with the grandma  the child is either sick, hurt, going to the hospital or hospitalized for being too sick. 2 weeks ago the baby got deathly sick out of "nowhere she claims" after being sick the baby stayed a week with grandma no problems. Been back with her 2 days and already bf got a text saying she dislocated her shoulder and elbow. I really think it's starting to look as she don't know how to look after and protect the child... Idk though. Just always something wrong.