Some women can start menopause earlier than others. Check in with your gynecologist for blood work and they can tell you for sure if you are starting menopause. Even if they think you are young for it, ask for the blood work and they should do it.
It could be. Improve your nutrition, take supplements. Consider using soy supplements, although they do raise your estrogen and are therefore controversial. But I suspect it is safer than hormones your doc could give you. I also take a yam supplement. These work for some people and not for others. Soy worked great for me for a good 3 years. Then I started thinking it was contributing to hot flashes, which it can do by messing with your thyroid. Stopping it resolved the problem. It was very good while it worked.
I want to let you know that I had a similar experience when I turned 40 (I'm 45 now). I had no idea what hit me. I was anxious. I would cry at the drop of a hat. I was scared. It was horrible. My OB told me that I was experiencing the effects of perimenopause. She told me that she can put me on low dose hormones or prescribe anti-depressants/anxiety meds. I opted out and did some homework. I started running 3 days a week. Stopped caffeine (since that made me anxious) and ate healthier. Took supplements (calcium, magnesium, b-complex, vitamin d). Used over the counter progesterone cream. I started feeling more normal in a couple months. I eventually stopped using the progesterone cream. It's been 5 years since it all first started. I'm still getting my normal periods, but every now and then, I feel the "dip" and that's when I make sure I do all the above and start the cream again. It seems to get me through. I think it's a long battle. I hope you're feeling better and have found a way to manage your symptoms.