DH and I have been having a difficult time of late. He was made redundant a couple of months ago, we have a 5 month old dd and things have been tough. I'm battling bad PND, and haven't been great to be around to be honest. I'm finally seeking help for it, started medication yesterday and have been seeing a therapist.
So as not to drip-feed, we aren't currently living together, although he lives a minutes walk away and is over all the time. We are not separated, I moved into the family home first whilst he stayed in our rented home until the lease was up.
I think he's having an affair. I have no concrete proof, but things are slowly coming to light to point in that direction - he had scratches on his back last week, and when I asked him where they came from he couldn't give me an answer. Just "I must have slept funny" 
Today I have just found a balled up pop sock on my sofa which is definintely not mine - I don't own any. He came over last night and slept on the sofa as dd isn't well so we coslept. It can only have come from him, it was scrunched up so I assume it was in his pocket and came out when he took out his phone etc. He's also very secretive with his phone, doesn't leave it anywhere and has a passcode on it which I don't know.
Am I being paranoid and anxious due to my PND, or are these things that would worry others also? I honestly don't know what to do.