Can a massage make plantar fasciitis worse?

No. However, word of caution:  If you massage the plantar fascia itself while it is in the acute phase (the most severe phase) of plantar fasciitis, you risk exacerbating the pain. It should only be massaged in the chronic phase, after the acute pain has subsided.

Deep tissue massage is particularly beneficial because it loosens severely tight tendons, ligaments, and fascia, allowing them to relax back into their usual posture. Apply a small amount of moisturizer or oil to your hands first. Consider your foot to be a tic-tac-toe game board. Massage your foot along the entire length of the arch, from heel to toes, with medium-to-firm pressure.

Then proceed across the arch's entire breadth. For about two minutes, massage each foot. This results in fascial release, increased circulation, and decreased tension and rigidity in the plantar fascia. Apply ice to each foot after you've finished massaging it for around 15 minutes.