Due to unforeseen circumstances, I have to change my travel dates which leaves me with a 30 day stay in Thailand, 5 days in Singapore, and then 2 days again in Thailand. All travel is done by plane via Suvarnabhumi airport. Will they accept the second entry without a problem – or is it too close to my previous stay? Thank you in advance.

No problem.

If that’s your only recent stay for tourism you shouldn’t have any problem.

if a person is not a perpetual tourist, there should not be any concern. If you're a tourist, you will be treated as a tourist like 40 million or so but if you pretend to be a tourist by living here for the "lure of Thailand", then it is a hit and miss and nobody can guarantee anything. 

Thank you guys!