I am worried about my eating habits

Hi,

I am worried that i have a problem with food. I don't think i have anorexia, I know i am not fat... I know i am actually pretty skinny and don't need to lose weight... but i feel like this is also the rational part of my brain saying this and sometimes that part isn't always in control.

Its like i know i should't lose weight, when i do i look ill, but something inside me wants to and it sometimes tricks me into letting myself.

It isn't a permanent thing, I go through phases of about three to four months where the rational part of myself is overtaken by this irrational desire not to eat. when the rational part of my brain isn't in control i feel like missing meals is an accomplishment, It makes me feel proud, like i have achieved something.

I am 5ft 2, the last time i went through one of these phases i think i dropped to around 7st (100lb ish) normally i am around about 8st. One day i nearly passed out which kicked in my rational brain again and i started eating normally again.

I don't know what starts or stops these phases, i try to avoid exercise because when i took up swimming again it triggered one of these phases, I was going to the pool 4 times a week and swimming 100 lengths, if i couldn't do the whole 100 i would get really angry with myself.

I am 26 and they have probably been happening once a year for the past 5 years but last time it was a lot worse. I am worried because i can feel this cycle starting again.