Teething or sleep regression

How have you all been able to tell the difference between the two. My LO has just turned 7 months she been sleeping through the night for the past month, until this week! She has been very hard to get down waking once or twice in the night an again very hard to get down then is miserable during the day compared to a very easy happy baby, she has turned ferrel (totally not used to this) I think its teeth but not sure

I cant see or feel teeth (ftm i have no idea what im feeling for)