Pls help

So lately Ive been going through periods of times where I’m really sad for no reason and I’m so sensitive and overwhelmed so easily and I don’t know why, I’m thinking maybe it’s just mood swings and birth control? But it’s scaring me because last year I went through a rough patch mentally for a good 4+ months (ps I hadn’t used birth control yet back then) and felt suicidal and wanted to ask for help at a certain point but I ended up just living life and coming out of it by myself :) I’m just scared it’ll happen again without me realising, last year I was scared of myself and the thoughts I was having and now and then I go through periods for a week or 2 like last year then I’m fine & happy again. Right now I’m going through a sad moment and I don’t know why and I just have the urge to fully isolate myself and not talk to anyone, it hurts my head and makes me disappointed in myself why I’m crying so easily at everything that happens and so sensitive to everything. Please help, am I just overreacting or having major mood swings?