Help! Almost 3yo son biting, hitting and spitting.

I'm not sure if this is typical behaviour from a typical three year old (he's three at the end of August) and we are just being typical first-time-toddler-parents, but my husband and I are at our wit's end.We have a two month old daughter and I'm not sure if her arrival has fuelled all of this behaviour to get worse suddenly, though he seems to genuinely love her and doesn't seem to 'blame' her for anything, nor have we been having a very difficult time giving him attention (I don't think he's jealous of her.)I really want to avoid spanking but when he gets into a biting/hitting/spitting headspace there is no reasoning with him. He either wails/cries endlessly until something distracts him and going anywhere near him results in being bitten or smacked. Sometimes he just screetches whenever you try to talk to/reason with him (when he isn't crying.)This behaviour sometimes comes from us asking him to use the potty, from him not getting the right shaped plate, from not being allowed to watch TV etc.etc. Sometimes we're play wrestling and he just gets too riled up and it turns to biting and when we stop everything abruptly to talk about biting he gets angry and everything goes downhill.He's perfectly capable of verbally communicating, we have no issue with his speech.We had some problems with him biting at daycare about a year ago but we'd thought he'd grown out of it/learned how to talk and that seemed to help communicate (like saying 'you're hurting me' or 'stop' instead of just biting.)At this point, trying to be patient and get down to his level and explain that he's hurting us physically/hurting our feelings does absolutely nothing and he will just continue to bite. My husband has lost his temper entirely and had to leave the room multiple times-- we've both got nasty bruises from his biting. I'm worried at some point he's going to turn his teeth on our daughter (she's heavily supervised when they're together for this reason.)It's frustrating, too, because 90% of the time he is an absolute sweetheart and so gentle and loving but then there are these spurts where he's a little hellion and it seems nothing will break through and we're ready to tear our hair out.Edit: I got on a rant and forgot to say that whenever he does bite/hit we put him on a timeout. We usually let him sit and scream/screech/cry for two minutes before we go and try to talk to him at which point it usually depends on just how worked up he is whether he bites/hits us, spits in our face, screeches at us or actually gives us a hug and says sorry. Lately the likelihood of the latter happening before some SERIOUS timeout time (like 15-30 min) is really slim. via /r/Parenting http://ift.tt/28UiTwQ