It is soooo hard doing it on your own when they are grumpy isn't it. Even the most serene calm mum would be driven to insanity I think! My 15mo DD did this to me a few weeks ago (DH works 10+ hours a day and barely gets to see DD or help me) and I was beside myself with frustration. At first I thought it might have been the unveiling of the toddler personality when everything I did and she tried to do led to screams and grizzles.

Hindsight was the answer for me, a rash showed up after 4 days of this behaviour started so I realised she was actually sick. Adding up all of the little signs through the week, being off her food, waking at night, wanting more boob, grizzliness made it look really obvious... in hindsight! At least, there was nothing different that I could have done for her - it was just a ride it out virus, I just wish I had known for my sanity.

I am not sure if this is the case for you of course. The unpredictability of your DH's work pattern (at least in your DS's mind) could definitely be the cause of a bit of his unsettled-ness, but he sounds well attached to you when he isn't having his "bad" times and this should be the most important thing for him so I don't really think it explains all that you have described.

I guess what I am saying is that if your DS is generally a really happy boy, there is probably something physical going on. Maybe if you sit it out, give more cuddles (and BF if necessary) the truth will raise its head soon. If it would ease your mind and help you mentally cope better - absolutely take him to a GP, they might help you add up a few symptoms you hadn't really noticed (like me!)

One last consideration: it could be the cutting of his molars. I imagine they are more painful than the smaller teeth at the front and they can cut at his age. They could be causing more grief than cutting teeth has before.

Best of luck sorting it out and making it through till the return of your DH, I hope your beautiful boy re-appears very soon.