What to do if I'm experiencing chest tightness and dizziness after taking methylphenidate?

i'm 19 years old. i don't have good psychiatrist here in bangladesh. so i've been talking methylphenidate for some time. i started with 10 mg gradually increased to 20 within 15 days or so. now it's been around 20 days i'm taking it. Today i took it around 5:00PM and suddenly i have chest tightness, chestpain, trouble breating, and i feel dizzy. I don't have access to a doctor. i cannot stop my medication because without it i cannot work. So it'd really be helpful if anyone told me how to take the medication and what to do now.