Potty training - going backwards....

So we've been potty training for around 6 weeks now and up until 2 weeks ago he was progressing really well, going to the potty unprompted and prompted. He was holding it in too and then my parents had to look after him so I could work for a day and a half and we had a few more routine changes and then it just started going down hill, he doesn't go to potty any more really unless he's taken to the potty, doesn't seem bothered by soiling and wetting himself. I don't know what to do, I'm frustrated and confused. He just doesn't seem to want to use the toilet or potty. Has anyone else had something similar happen? Some advice at the moment would be amazing, I just feel at a loss of what to do to get him back to where we were....I don't want to give up as we've gone so far...