Hi , thank you so much for reaching out here. I'm sorry to read that your symptoms have been impacting your life so much. You're definitely not alone in this struggle. I hope the methotrexate will help get your symptoms under control. I've been taking it for quite a few years now and it has really helped me, although it did take a while to kick in and we all respond differently to these things.
I think seeking a second opinion if you are unsure/unhappy about your diagnosis is a good idea. A lot of us (myself included) entered a bit of a denial phase after being diagnosed. This diagnosis is a LOT to take in, and it also doesn't help that there's no specific test for psoriatic arthritis. It sounds like you have quite a strong family history of psoriatic disease. How do your symptoms compare to that of your mom and brother?
To answer your questions - yes, unfortunately flares can last for that long. Looking back, I believe I was in a flare for five or six years. I was untreated during that time though so I'm sure that played a part. The following article has some infographics that I thought you might find interesting: https://psoriatic-arthritis.com/infographic/when-your-psa-flare-is-flaring As you can see, around 22% of respondents had flares that lasted for longer than six months. With regards to why all of a sudden - sometimes there seems to be no rhyme or reason for these things, but often there is a triggering event. Here's some information on common triggers for PsA: https://psoriatic-arthritis.com/psa-basics/cause-triggers Do any of those seem feasible to you?
I hope this is all of some help. Please remember that this community is here anytime you have questions or need support on this journey. Sending gentle hugs! -Catherine, Community Moderator