taste advice

I have now had my brew in the kig keg for about 2 weeks and the pressure has really built up now. I gave it a quick try and at the moment to tastes odd, a slightly sour start with a sweeter mid taste and a bitter finish (really messes with your head)
The brew is a muntons best bitter so I just wondered if anyone had tried it or if they could advise if this is normal and it just needs a couple more weeks before drinking.
method used for ref: 4 days in primary, week in secondry then into king keg with 4 oz of sugar to prime.
Cheers
Mark

Someone correct me if I'm wrong as I have yet to keg my beer, but I've heard the first few draws from the homebrew keg (corny keg) pulls alot of yeast and some sediment and may not taste the best. After which point you should be fine. If you have friends like mine, they'll drink it anyway! Besides a bad batch I may do will probably taste better than the watered down stuff they're used to drinking. Relax, don't worry, have a homebrew.

Could be a bit more yeast in the first beer. That's normal for kegs.