dude strands congoing with other strands = dreads... you probably had mini-dreads that were maturing and waiting to eat other ones.
and SE is right finger combing is combing nonetheless.
seriously don't bother with crochet, you're setting yourself up for failure because not only will you not see the results STAY PUT, but you'll also disappoint yourself mentally when you find out you spent all that time and it didn't work. after all, you might be thinking a week's worth of progress is good, but try not touching it. a weeks worth of work may be even better.. whatever works for you man. experiment!!
its vital to keep your hair clean WHILE spacing out your washings to let your scalp adjust. wait too long, and the oils will mess up the progress... wait too little, and the water running through will mess up the progress. it's give or take, and that's why the first couple months are the hardest because of how messy and oily it can get, with the results being ummmmm really hard to see. with my length of hair at the time, yeah very very hard to see.
that and you really should be observant to how well your washing process is working.. experiment.
the best way to look after your dreads is to not look in the mirror. what a paradox you might say.. well, for the record i look @ the mirror at least 5 minutes a day just to watch the progress. sure i think about it more often, but it's very fascinating
. i'm takin it all in.
now... your scalp was pulling tight because sea salt encourages your hair curling, twisting, moving around as it dries. but putting acv and lavendar oil is not at all necessary. in fact it is hindering progress because acv is conditioning (you dont need that), and lavender oil is still oil. 1 drop isn't bad tho.
they WILL unravel, undoubtedly, especially since your hair is extra oily cause of the change in washing. that's why it's important to wash your hair thoroughly each wash, that way there's no buildup. dry hair moves around and actually has a chance to knot, whereas oily hair can't (obviously).. same reason why wax is worthless. of course, washing too thoroughly is also easy and by that I mean touching your hair too damn much.
don't think too deep into it.. you can't really control dreading other than using sea salt, wool, and keeping it clean AND dry. and when i mean dry i mean not touching water and also not conditioning.