Bbt charting question?

I had a chemical pregnancy in October and finally had my first textbook cycle this month.Had my period Nov 17-24,then O'd on the 1st(bd'd the day before as well as the day of,and FF confirmed O). Unfortunately right after I ovulated,I caught a bad cold and for the last week have been sleeping erratically,waking up every hour or so then I can't breathe,etc etc.DH also dropped the room temp so I could breathe better.At 7 dpo(wed) I had a HUGE dip in temp,as in .7 as well as cramps which I never get,it actually went below coverline.I am still about a week out from AF so a temp drop would be early as mine doesn't usually do that until a day or two before the witch is due :)This morning temps are back above the coverline but my BBT usually doesn't get above the mid 97's.So it's not the temps themselves bothering me because I know I ovulate and such but I am wondering about that big dip.The last week my chart looks like the Rocky Mountains due to the cold so I can't pinpoint a reason,DH and I are ttc so every cycle is important.I had someone say it could be an "implantation dip" considering the timing and the cramping that accompanied it(those stopped last night as well,just had them for a day)but others say that's a myth.Can anyone give an opinion on what it might be and whether I should just ignore this? I know one individual temp doesn't mean anything but I'm curious to know if a BFP might be my christmas present.Thanks!