Per previous postings, I know he visits his Dad. Perhaps, is his Dad "teaching" him different? Or doing something that got him un-enthusiastic about it? I mean, sometimes, what I "let" my son do, is then "undone" by my well-meaning Hubby... but in total ignorance of what I am trying to teach our son, or "let" him do.... Just a thought.
For instance, my son likes to put on his own diaper cream (I give him just a drop), and it's okay with me. I'm proud of him. But, my Hubby on the other hand, doesn't 'like' him to do this...and Hubby will tell him 'no.' Then my daughter will chime in and tell Daddy "he's just trying to do it himself... Mommy lets him..." (sigh), and then so I realize I have to "explain" to my Hubby that it's okay... I don't see it as a "bad" habit.. but that our son is getting self motivated and independent and "caring" about his routines/hygiene. I like to encourage my son that way. No big deal. They are learning...
But yes, sometimes toddlers just go through spurts of changes... one minute one thing full of gusto, then next time not so much.
My son is doing that too sometimes. Other times, he refuses to change his clothes and just wants to wear the SAME thing everyday! So well...
My son is not potty training either, and I'm not in a hurry either. But sometimes, he takes off his own clothes or diaper and wants to, other times he doesn't want to AT all.
Hot and cold.
Just give him time... he's still so young to be doing it CONSISTENTLY. For my eldest child... it wasn't until 3-4 years old that she was doing it consistently. It's a process... I wouldn't worry about it. Toddlers are so fickle. He will get 'motivated' again... just make sure he is fine.. or ask him "why"... or if anything got him to "not like" changing his clothes.... ?
All the best,
Susan