Cracking noise?

Its Raleigh XXIX with an EBB so i thought the EBB was creaking but i knew for sure that it was not slipping. So i took off the chain, rear wheel, cranks and removed the EBB. I cleaned and regreased everything, put it back together making sure i had a good chain alignment and the cracking noise is still there. I inspected the frame(steel) but no cracks.

Rode it around a bit to try to understand the problem. It makes the cracking noise when mashing. Then i noticed that while pedaling along the noise was also happening, just not as loudly. I have never had a problem until yesterday. In fact the noise wasnt even there when i left my house, it started just before i hit the trail. As far as i can tell there was no gradual noise building up, it just happened all at once.

So, im thinking it might be the rear hub. What can i do? Clean/regrease it? The wheels are WTB speed discs and the bike is only about 5 months old but gets alot of use. It has also been very dr and dusty so i have sprayed the bike off with a hose a few times but i never put it up wet. Please help.