If he's got a blocked up nose, go to your nearest pharmacy and ask them for some saline drops. You then drip a couple of the drops into each nostril before feeding and it disolves all the crap - really does work too! dd got a really bad cold when she was only 3 weeks old and then helped us a lot. She also had green poo in her nappies too and the doctor also said that this was a sign of her fighting an infection and nothing to worry about.
I imagine that he will have vomitted because of all the mucus in his throat as babies can only normally get rid of it this young by throwing up.
I would say, keep doing what you're doing, offer feeds often, like every hour just in case he feels like some and keep checking his nappies to see that they're still wet. If at all worried though, do go and see you GP - doesn;t do any harm and will certainly put your mind at rest.
On the temp front, since he's over 3 months old you can give Calpol in half doses (2.5ml) - or if you prefer, just strip him down and/or bath in tepid water to keep him cool.
Hope he feels better soon.