I'm new to this board so please be gentle. just need some advice on the best way to get my nearly 3 yo DS assessed for possible sensory processing disorder or something similar perhaps. have long had my suspicions that something wasn't quite 'right' - he was a miserable baby that was impossible to get to sleep particularly at naptimes, cried so much, got hiccups frequently, seemed to need a ton of stimulation but just a little too much would tip him over the edge.
I raised concerns at his 2 year check with the HV about his hyperactivity and epic tantrums in which he seemed completely unable to be calmed (amongst other things) she told me he likely was just sensitive/a bit anxious and most likely as he was so bright (her words not mine 
) his mind took him to places he wasn't able to handle emotionally. I decided to leave it until he went to nursery at 3.2 to see if anything was noticed there (although he's an absolute Angel at groups, it's at home/on my own with him I have trouble) but things have got worse since we moved a couple of weeks ago (understandably, it's a big change) and I've been reading a book called 'understanding your child's sensory signals) and have identified with over 50 of them that completely sum up his behaviour and make so much sense to me.
I don't wish to label him or self-diagnose but if there's anything at all we can do to help him and make learning/growing up easier then obviously I'll bend over backwards to do it. I also think he has a posterior tongue tie, probably not relevant but I do wonder if the two are connected.
I just want to help him handle his fears/struggle with things such as managing transitions and his huge meltdowns where he just seems completely out of control, sometimes screaming for hours, nothing seems to help.
I feel like he has 3 types of tantrum. the first is what I consider the normal 'pissed off' kind of toddler tantrum which I tend to ignore and it's over in a few seconds. the second is through frustration where I help him take some deep breaths and then try again. the third comes from nowhere, appears to be about nothing and goes on forever, he seems completely unable to snap out of it, completely encompassed by it, lashes out, goes red in the face etc. sometimes it seems to ebb and flow, he'll calm for a minute and then sometimes remind himself of why he was upset (if it started with being told no about something he'll often ask again when calm and then kick off again when told no again like he's not done) - my belief is that stress has built up and built up and he's no longer able to 'hold it together' - he often has this kind when we return from a trip out to a group or shopping.
his language/speech has always been great, he has been talking since 14 months, seems to have great understanding, is shy but starting to build connections with people but only adults at present. he's only interested in a couple of children, mostly older.
anyway the thing is I think I need to get him referred to see an Occupational Therapist but have no idea what the first step is...should I speak to my GP or HV? I'd appreciate any experience or advice, thank you if you've read this far