I get it coz I wear high heels alot and i have tight achillies tendons. Wear shoes that fit well and allow you feet enough room. Do some flexability exercises with your ankles and achillies and take paracetamol and brufen.
A good ankle exercise is to point your toes then imagine you are writing the alphabet in big letters with your big toe, also standing with the ball of your foot on a step and allowing your foot to flex downwards and holding it flexed for a least 30 seconds will stretch your achillies.
Yes OG I am well aware of it, having more supple ankles is one of the ways to help eliviate symptoms as it helps your foot to move correctly when you walk and thus pay corrct any problem causing the metatarsalgia. Just because it is the ball of the foot that is hurting doesn't mean that it is the place that needs treatment. Like I said I have suffered from it coz my achillies has altered my pronation.