Hi tgm, my six month old is teething at the moment (her first teeth at the front). She has also had a cough, a cold, and diahorrea and sickness, all in the space of a fortnight - oh what a happy household we have had lol!
Before getting poorly she would have her bath and be in bed by 6:30 and sleep thru til 7am, but since she has been ill she has been clingy and wakes thru the night. I would say it is just a case of sticking with it. Last night I was up on the hour every hour (like you, I am currently falling asleep into my keyboard at work) but it is getting easier to get her back to sleep. She doesn't moan or seem to want anything when she wakes but thinks it's playtime lol.
When she was very poorly / painful gums, the pharmacist gave us Calpol Night which helped tremendously, she would still stir in the night but easily settled and go back off quickly. I would stay just stick with that routine and be tough, you're doing really well, eventually he will be back in his old routine xx