I've tried to start meditating a couple of times in my life but every time after a couple of days instead of being introduced to gradual calm/bliss/joy/whatever I get met with an existential dread, sadness, anxiety, melancholy etc. I guess am naturally predisposed to those as well, much more than 'happy' feelings. I had to then take a week or even more to recover. I feel like you need to have your shit together so to speak before you try meditating or it might uncover some suppressed trauma or whatever it is. I must say though I am way more 'aware' of my body and emotions more than before, but the problem is they might not be pleasant. It is okay when the feeling is transitory but an existential dread which lasts for days or weeks feels impossible to shake off, it consumes your whole life. One day I hope to be able to swing the pendulum in the other way.
I believe that half of meditation is letting your self dredge up all the nasty stuff and watching it happen, the other half is cultivating an outlook that's okay with or even happy with those things coming up. It's literally practice, for remaining stable when bad things happen "off the mat", and to be able to narrow in and concentrate on the grain of calm/bliss/joy in every moment. These elevated jhana states can be a healthy part of that, but they take work to get to.
if you're going to actually try to do it and not just try to McMindfulness your way out, it's dangerous to go in to this unprepared, IMO. early in my meditation experience I went a bit too deep on this just by practicing insight a few hours a day on one of the apps and was anxious and emotionally unbalanced for months.
Finding a meditation teacher or practice community may help, too, it continues to help for me, but it's one of those things you gotta be ready to keep going back to
To share my own experience, I first tried meditating seriously in the context of a 9-day retreat and the first 4-5 days were as you described. Anxiety, melancholy, boredom, frustration, then a period of emotional catharsis and much more enjoyable meditation after that. I think it really depends on how much shit you're repressing.
