Is There Possible for Any Side Effects from Botox Injections (In the Armpits) Which Have Been Applied 1 Year Ago?

The effects of Botox to the underarms can last up to 6 months, it is highly unlikely that your Botox is currently causing these effects 1 year after injections. I recommend an in-person examination with your physician for further investigation.
I've created a video that reviews treating underarm sweating with botox. I hope this is helpful in your research! 

I inject Botox in the underarms more than 10 times a week and I have never seen this or heard of this problem. We typically give 50-100 injections to deliver the amount of Botox and I do not think that your lumps, bumps are related to Botox injections. Hydradenitis ? Seek a dermatologst to help you out.