Hi Katie, I am glad you will start oil pulling. There has been a lot of different experiences documented on this forum as to what oil works for people. For me it is coconut oil and a few drops of oregano or - my latest addition - oil of black cumin. I also use sesame oil and find it very nice. I am sourcing fresh olive oil that is organic and will report when i start on it. I have heart that is helps with the bones:)
But of course different oils work for people slightly differently, so the best way is to test it for youself by trying different oils over time.
But the good think is, you don't have to do it all at once. When starting any oil is good, preferably without pesticides in it. It sounds like your gums may be infected so i would say coconut or sesame are the best - as they have antibacterial properties that will be extra helpful for you.
Don't rush into testing many oils, just decide on one that appeals and buy it and then start using it daily. I also would not rush into adding any extra oils like oregano at the beginning because just plain oil is enough at the beginning. You don't want to overburden your body with too much die off and detox.
I found that after a week of feeling great the detox caught up with me and i spent entire weekend feeling like if I had a chronic fatigue - I could hardly move. Tis is when i discovered high dosing on vitamin c (actually I got liposomal to spare myself the trouble of taking lots of Vit c powders) and the symptoms lifted very quickly. This is why i believe it is good to add vit c - in very high doses, not one just one or two tablets, to your pulling routine.
Hope that helps:) and please let us know how you go. You can browse this thread for testimonies, there are many enthusiastic reports here of profound changes that people experience with OP.