I think both ideas are good.
Notice they both use salt?
I'd try both ideas. Oil pulling first, then brushing and/or swishing (you might not be able to brush right now) with salt water. I'd suggest getting or using Celtic Sea Salt
(it's grey) at the first opportunity, because of the micro-minerals. In addition to that, you could try oil pulling first, then brush (or swish) with a little baking soda mixed with water (make a paste for brushing by dipping a wet toothbrush into a pile of it on your hand) and following up with a salt-water swish/gargle. The reason I suggest this is to kill some bacteria/fungus and reduce the acidity in your mouth. As a side benefit, you'll find your teeth getting really white within a week.
You should look into the acidity levels of your body. It sounds like your body is too acidic now, and that invites infections. To check that, you can get pH papers or strips from a well-stocked pharmacy or from the aquarium section of a well-stocked pet store. Phone around first, as they're hard to find. You can also get them online if you can't find them locally - Vitacost sells them, and delivery is fast. Each morning as soon as you get up, and each evening before going to bed, spit on a strip of the pH paper, and urinate on a different strip of paper. You want a pH of around 7.0 - neutral. The box or "tape dispenser" pH strips come in have a chart on the back or side showing what the colours mean. If the paper turns yellow, you are very acidic (the chart will list the pH values as well). If the paper turns green, you are a little acidic. If it turns blue-green, you are neutral, and if it turns a deep blue you are mildly alkaline (which is ok). I'm willing to bet your levels are lower, around 5.5 - 6.0. When you raise your body's pH levels, your immune system can fight any infection more quickly and efficiently. To raise your body's pH levels, juice vegetables and drink them every day, at least while you're sick. If you don't have a juicer, any vegetable juice will help - organic is best. The juice will help your nutrition if you can't eat right now. This is a side issue, but it might help.
You might have canker sores exacerbated by nerves, or you might have another kind of infection which you might have picked up from another infected person coughing or sneezing nearby or in the room.
Once the pain is reduced in your mouth, I have 2 more suggestions. I sometimes get a canker sore on the back gums of my teeth, or the inside of the cheek next to the gums. I've found that eating 2 apples a day, one in the morning and one at night, for 4 days, gets rid of the canker sores. Of course, you could eat more apples, to make healing faster. The entire apple, skin and all. The most active ingredient seems to be in the skin or next to the skin. Juice doesn't work. This simple method has worked 100% of the time for me. It's faster if you can bear to chew the apple slowly and move the juice around to the infected areas. The first time, it stings like hell, but you'll notice the pain going down quickly. After that, it gets easier, and by the end of the 2nd day you'll notice the canker sores are healing (if they are cancer sores). They should be gone by the evening of the 4th day.
After the inflamation has gone away, you could try swishing and/or gargling with oregano oil. It is an anti-bacterial, anti-fungal agent which is as strong as anything you can get from the doctor. It usually costs about $25 - $35 per 1-ounce bottle, and usually the bottle says 2 - 3 drops in a little water. It burns, though, so it's out of the question at this early stage. I take a much higher dose, as I'm fighting a long-standing fungus infection on my hands and feet as well as the inside of my lower lip, and I've found it's ok to take up to 6 drops a time, 2x a day. That's a pretty high dose, though; it's probably best to follow the directions on the bottle. A 1-ounce bottle will last months. You want to kill whatever is causing this infection so that it doesn't come back and so you don't accidentally infect your girlfriend.