My situation:

Arrived in Thailand about 1 yr ago. Have used 3 visas on arrival and one 3 months tourist visa in the first 6 months. I used 2 tourist visas in the next six months. They were all single entry.

I am considering going to Macau to play in the APPT tomorrow. I would be gone for 5 days but I'm not sure if I could get back in. I only need another month in Thailand before I go back to the USA. Also I lost my passport in the past year and had it replaced so I don't have any visas on there other than my current tourist visa.

Can I go to Macau and return to Thailand on a stamp visa? Can I get a 4th tourist visa. Never at any point was I outside thailand for >3 months during a 6 month period. Although I was probably out for about 3 months total over the year.

Please let me know ASAP if you know this because I will be buying a flight ticket in a few hours if this works.

You should not have any problem getting a visa exempt entry as you at least four months since your last one.