How long can i re-enter to Vietnam?

Hi! I am a Filipino passport holder. I am backpacking in Indochina, HCM-Phnom Pen-Bangkok all in “6 days”. But My exit back to Manila is HCM, so I will be flying back to HCM from Bangkok, and since I have a 7 hrs. lay over at the airport, I plan to go to the city in HcM once again for the last time and will do a last minute shopping. Now my question is, will the immigration allow us to re-enter again since our last enter was 6 days ago? Anyways, I have a proof that I am leaving the same day through my return flight ticket. Hope to hear some good and accurate answers.

Thanks!