Doctor thinks toddler had a staph infection but I think it’s an injury!

I’m taking him to a different doctor tomorrow but I took him to urgent care today because my 2 year olds ankle swelled up last night, he couldn’t put weight on it and cried for comfort or to be carried because it hurt. So today it was still swollen but not as painful because he could put more weight on it l. We took him to urgent care and the doctor said oh it’s a staph infection or a swollen mosquito bite... I told him over and over again I really didn’t think it staph and mosquito bites never make him swell like that but he prescribed antibiotics and sent us on our way. I decided I wanted a second opinion so I booked another appointment tomorrow with a different doctor. As an athlete who has experience different injuries I am pretty familiar with the symptoms but I would like others opinions. My son can’t talk yet so it’s hard to know what’s really going on.

His symptoms are:

Swelling around ankle and redness at the joint bones

Swelling also goes up his calves

Swollen spots are warm to the touch.

Mild fever of 99.0

Mild pain when walking on it

Pictures of the ankle:

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The black circle is marker to track the swelling

UPDATE: guys I didn’t say I wasn’t going to give him the antibiotics, he’s already had his dose today I’m just asking if it could be an injury. Please don’t go assuming I’m not giving him what he needs I just want to cover all aspects.