I recently found a lump in my armpit. It's pretty painful. I now have one lump in my armpit that are slightly black. Cancer symptom?

Armpit lumps. Require a doctor licensed in your area to examine as have a variety of causes. This will help sort it out and allow your question of cancer to be addressed which we can't do without examining the area. Here is some general information on causes: http://www.healthline.com/health/armpit-lump#overview1 All the best.
Agree w Dr. Ram. This could be an inflammed lymph node, a cyst etc. Don't jump to the conclusion that this is cancer-but do get it checked.

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I recently found a lump in my armpit. It's pretty painful. I now have three lumps in my armpit that are painful and slightly red. Cancer symptom?

Not really. Cancer in the armpit essentially represents metastasis to the lymph nodes high up near the axillary vein. They are for the most part painless and would not be associated with redness. Rather one would expect inflammation of the sweat glands right under the skin for which warm soaks and possibly antibiotics would be effective. Read more...