Complaints

I assume you are speaking “generally” rather than “specifically”. -

There are a couple on reddit you might like - 

Reddit.com. Support for Caregivers 

Reddit.com- Caregivers 

both seem to be active with several thousand follower/members - take a look at their sysnopsis to see if what you want to say fits - seems to me it does if you just want to rant or have specific question.  

I don’t do facebook so can’t help you there - 

Then there is always here too -