Sleep regression?

I m so so confused and hopeless:( My baby 5and half months old and she was a very good sleeper Expecially in the night but this week been a nightmare and I really don’t know if it’s sleep regression or something else . She waking up sometimes in the middle of the night and so so hard to settle her back . If your baby had has sleep regression please can you tell me how does it looks like ? And also tell me it’s gonna end :(