Help with my 11 month old?

He woke up 7 times in the night last night and the sleep he did has was very restless. He's had a streaming nose for a couple of days but no other illness symptoms. This afternoon he had about a 2 hour solid block of unconsolable screaming, he's just fallen asleep now. He's completely off his food, ate very little yesterday and won't eat anything today - he had 14oz milk in the morning as usual, I've tried to give him a bit more milk this afternoon to make up for the lack of food but he won't take that either. He doesn't have a temperature, rash, constipation or diarroeah - nappies are all as normal. He may be teething mildly but he's only just had 2 more through last week and he's not acting how he usually does with teething pain - he is dribbling lots but no gnawing on anything and no relief when chomping on anything. I've tried all name of different foods, table foods, yoghurt, even puree, nothing. Any idea what I can do for him or what might be wrong? This afternoon has been like being thrown back to the newborn days - first time in as long as I can remember that I haven't known what's wrong or what I can do!