Hey hun,
We had a similar issue with Caden at 12 weeks. We ended up going to Ngala (similar to Tresellian) over here in WA and they sorted him out for us. We had to teach him to settle himself to sleep, which pretty much involves us observing tired signs (rubbing eyes, grizzly, yawning etc) and putting him to bed awake so he can fall asleep on his own.

It took alot of work, 2 days of crying and lots of tears from us, but we got there in the end. Now he is generally pretty good (except when teething).

I found that although there is heaps of advice out there, it was so hard to let him cry. Ngala taught us the difference in cries, and different techniques to use to settle him in his cot, rather than picking him up or feeding him etc.

Perhaps give your parenting line a call, as it can be pretty hard on you at first. Like I said, it took 2 days before Caden eventually fell asleep on his own. AND he learned how to suck his thumb at the same time which means he sucks HIMSELF to sleep now, LOL.

good luck hun!