I cured erythema nodosum with SSKI drops taken internally.
Erythema Nodosum Remedies
Hannah, a very quick look at the condition suggests it is brought on after a bacterial or viral infection, thus an attack on the immune system. Research suggests anti inflammatories, you could try turmeric capsules, aloe vera gel, I would highly recommend boswelia serrata as an all round and very effective anti inflam. The other researched suggestion was potassium iodide, which as Lugols Iodine, has many pages of testimonies here on EC. I would look at ways of building your immune system, vitamin c is one, and very good, and there are many others. With any kind of detox effort it is important to also support the liver, milk thistle extract, dandelion or other liver support blends. I would also add a high quality refrigerated probiotic from the health food store.
Best to you on your good health journey