Swollen bump on shaft of the penis? STD? Or pimple?

one night i just Noticed My penis shaft was getting itchy and next thing you know there was a swollen pea Sized bump on the Right side shaft on my penis. It’s not itchy anymore but there is still a bump and when I squeeze it it feels like there’s a pea Under my skin. It’s only been three days and it’s starting to look yellow and dry??? The first day it was super red. The pictures below are in Chronological order is this an STD?

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This is simply a Penile Cyst - they are not problematical and are linked to pressure most often caused with pressures within the body of the penis during sex, masturbation or any form of penile enlargement.
You must leave it completely alone as further irritation can cause it to increase in size and also take longer for it to heal.
You can still masturbate or have sex, just try to take it as easy as possible. If you happen to use any form of penile enlargement you MUST abstain from this as it could further irritate this, or even cause additional Cysts.
Unfortunately, they take their own time to heal and subside in size - and I am talking anywhere between several months ant the best part of a year. This is why it is so important not to further irritate it