thanks for you advice everyone

I have done some more research online, and in most cases it is very common and there is nothing to worry about. There can be many causes, but most of them are not serious, and just little things.

Like Shannon said if the nosebleeds last longer than 15 mins, or if he keeps getting them frequently, then maybe it is more of a cause for concern, and I will be taking him along to Drs, just to have a chat about it...

But gosh its really disturbing... it really got me panicked lastnight...

Oh, and I also found out that its not a good idea to lie them on their back as they will end up swallowing the blood which can irritate their stomach.
You're meant to pinch their nostrils shut and have them leaning forwards... however with a crying squirming toddler its not really possible.. #-o