I used to be good at school, now i can't pay attention and procrastinate a lot. could this be adult adhd or some other mental health issue?

Stress?: Sometimes when we are stressed, concentrating and procrastinating is common. If you were never diagnosed with adhd as a child, unlikely now. More likely anxiety, or depression. Stress can cause mood changes try organizing yourself as you would if you had adhd by staying organized, keeping an agenda, structure your day and take 10 minute breaks for every hour of study. Therapy can help too.

Psychiatric Consult?: Usually adults with adhd have had a problem when they were younger. There may be other issues. Why not have a consultation to explore this?

Not ADHD!: adhd is a developmentally derived syndrome that starts in early grade school. See you doc to rule out medical causes first. It medical causes are ruled out a psychosocial history may reveal a root problem there. Take care.

Need evaluation: if you did not have symptoms of ADHD as a young child, it is unlikely to be adult ADHD. You should start with your doctor for a general check up. If nothering found,, a referral to a neuropsychologist would be warranted.