Sad for no reason

Just after some advice or reassurance, I'm 22weeks pregnant  over the last few week or so I have been an emotional wreck, but generally feeling down and sad for no reason, I mean I can't shake it off and I've got so much to be looking forward too this year. 
I haven't spoken to anyone about it but over the last few days I've had a few "melt downs"  with obsessive cleaning and getting really pissed off at the most minute of things. I'm so so tired but can't sleep! I can't concentrate on anything at work or home.
 Not sure if it's just pregnancy hormones, I don't remember being like this last time at all, I feel I could cry all day or sit in a corner on my own not having to speak to anyone would be lovely!! I have always been happy go lucky with a smile and full of confidence but it seems to have disappeared I'm at a loss as to what to do 😢
Can anyone offer advice? Or been in this situation?