Hello Xsessa and welcome.
Have a good look inside the lamb's mouth. If it is split then it could need to be stitched by the vet (veterinarian), but if it is more grazed or only a minor injury then it will heal on its own. Use the blue spray on the outside, being careful not to get it into the lamb's eyes.
You will need to bottle feed the lamb and keep it from its mother or she will kick it again. Could you put it in a pen separated from the mother by just one divider, so they could see each other, and she could see her twin, but the mother couldn't kick her? Feed the lamb inside the separate pen.
There are ways to get a ewe to accept a rejected lamb but they are unlikely to succeed after a full week of rejection. Just resign yourself to raising the lamb on a bottle, but near its family for company and warmth.
Please let us know how things progress.