Two clinics that cater to foreign visitors and that do health check-ups are:
1. https://www.medconsultasia.com The owner, Dr. Donna Robinson, is a GP from the UK.
The clinic is located next to Samitivej Hospital on Sukhumvit 49/9 in the Thonglor area. Call them for an appointment at:
Phone: 66 (0) 20 187 855
info@medconsultasia.com
2. http://www.globaldoctorclinic.com/#
They cooperate with major health insurance companies so that your medical expenses may be reimbursed directly or indirectly. They are located in Silom across from the Novotel Silom:
Global Doctor - TMVC Clinic Bangkok
Ground Floor, Holiday Inn Hotel, Silom
981 Silom Road Bangkok 10500
Tel: (66) 2236 8442; (66) 2236 8443; (66) 2236 8444 Fax: (66) 236 8445
gdbkk@globaldoctorclinic.com
The heat and humidity in Bangkok this time of year can be overwhelming and causes your blood pressure to drop and your heart to beat faster...
I don't want to worry you but if you had chest pain or a pain that spread out to your arms or if you had any other signs of a heart attack, even 'only' an NSTEMI, you should see a doctor ASAP!
As pointed out by Ropey, a check-up at a private clinic or hospital in Thailand probably won't break the bank and you don't lose too much precious time...