P0022 CODE AND WEIRD SMELLING EXHAUST

Alright I have a 2006 Toyota Tacoma V6 Auto and I've gotten this P0022 code "A camshaft position timing over - retarded bank 2" twice now and its gone away both times on its own but did throw the CEL, now I've started noticing a very strange smell from the exhaust but not all the time only sometimes, not like coolant burning but something along those lines and my coolant reservoir is almost to the low mark seems connected as it was just full about a 2 -3 weeks ago during the oil change I do put around 400miles a week on my truck though and I know they are known to get a little low but this seems drastic. But there's no smoke. Some times it idles down to almost 500RPM and gets a little rough but then clears back up, could this be a possible blown head gasket? The truck only has 120k on it so I really hope not.