Apply a warm towel or heating pad to your hickey. Leave it there until the area is warm. Just be careful not to burn yourself. If you're heating up a pad in the microwave, make sure you follow direction and give it time to cool down.  Apply heat until your neck is warm enough  Do not apply heat to your hickey right away. You should only do this after 48 hours of getting your hickey. If you just got your hickey, apply ice and begin massaging the area. Once your neck is warm enough, use your fingers to rub the hickey in a circle, from the inside of the hickey outwards. This will help break up the blood clots and will improve circulation in the area. Drag your fingers from the center to the outer edges of the hickey. Remember to be gentle. If you apply too much pressure, you can make it worse. Take a break and try the massage again a few hours later.

How would you rephrase that briefly using Vietnamese?
Chườm nóng lên dấu hôn. Mát-xa dấu hôn từ trong ra ngoài. Nhấn tạo áp lực vào trung tâm dấu hôn. Lặp lại quá trình vài lần một ngày.