Awake in cot when he should be sleeping

It really has been a couple of rough and arduous weeks. Kien has been rather grizzly during some of his awake time and I've really had to play it by ear with when to feed and when to give him a nap. Night wakings galore as well and can be 1-2hr duration. Our routine is such a mess these days! Not only that I also feel as though all the hard work of sleep training these past few months have gone out the window and he can't even put himself to sleep anymore. I have discovered that jiggling him in the cot and also shh/patting his chest firmly will eventually get him to calm down and go to sleep. However it is like we are right back at the beginning with me having to help him for ~20 mins, sometimes longer - even at night after he has taken a feed.
I guess until we sort out whatever it is that is troubling him I need to be a bit more lenient with the sleep training and the routine in general. The pediatrician last week has prescribed a different type of probiotic to treat yeast in the stomach. She said that a clear symptom for babies suffering this ailment is waking up after 2am and staying awake. Today is day 4 on the new stuff so hopefully it makes a difference soon. She also thinks he is waking because he is hungry (every 2 hours?!?), so I've been feeding him when he wakes. The results are variable. She also says that 4 hours is a long time for him to go between feeds, and since he has a small stomach and actually lost a bit of weight in the last week she advised feeding him more often. So I have been feeding anywhere within 2 1/2 to 4 hours. This has certainly increased his daily consumption totals, but we are no longer doing the 4 hour routine that he has been on since he was 4 months - not sure if it matters anymore :/

We took him to Western Park at the end of our street the other day. We put him in the swing for the first time. He did enjoy that.

In 2 weeks time he is going to be 6 months old and starting back on solids. Perhaps by then the bacteria in his gut will be at a good balance and the food will help with keeping him a bit fuller so he won't wake so often during the night and allowing Jef and I to get some sleep. Studies have shown prolonged sleep deprivation evokes insanity....yip, I can feel it!