Everybody needs a diagnosis as step one. As Ollinger says, don't assume your injury is anything based on the very limited experience, knowledge and medical education of forum posters like me.
Everyone wants to spend $30 for a fix and continue playing tennis. With this approach, as you encounter injuries your risk of having a new injury lead to a chronic injury is greatly increased. Don't assume PF. Don't assume some rosy experience of a poster - who may not even have had your injury - applies to your injury.
For PF, I had it in both feet and mine got steadily worse over the year. I finally had to stop tennis completely. I stopped for 3 months and believe that was not enough time as there was still a little pain when I started playing. Research healing times tendons, ligaments, 'planter fascia' (whatever that is?), etc.. These times are in months and not weeks.
The calf muscles connect at the heel and the heel connects to the plantar fascia under the foot. Understand that tight calves pull on the plantar fascia so these have to be addressed together after the injury is healed. Heel pads that simply alter the angle of the foot don't seems like a good idea because of the underlying problem of the short calves. This is complex and needs a specialist and physical therapy. Short, tight calf muscles also increase the chance of Achilles injuries and calf muscle tears.
Exercises and stretches to prevent injury to healthy tissues are a completely different thing - not intended for injured tissues. Exercise and stretches could make things worse.
There are also life style issues that contribute to tight and short calves. How many hours of the week are your toes pointed? Sleep, watching TV, sitting, etc? How many hours are the ankles dorsiflexed, walking, running, tennis, etc?. Don't stretch your injured tissues without a Dr's approval and physical therapy.
Are your calve muscles held shortened 90% of the hours of the week?