Potty Training-HELP!!

Ok, so we started potty training almost 2 weeks ago- ditched the diapers except for sleep, and haven't gone back. The first week was encouraging. I was able to see progress each day and would take him to the bathroom every half hour and he would go 99% of the time. He still had accidents each day, but I expected that. This second week had been pretty frustrating. Pee everywhere. I've come so close to just putting a diaper back on him and giving up. I don't know what to do from here. Last week was great, and this week has been awful. There seems to be no schedule to his peeing, it's just whenever. Even if I just took him to the potty. He's super smart so I know he understands what I say to him, and he also knows before he pees because he will often stop and look down before peeing, yet he makes no effort to get to the potty. What can I do?!