Can resting sprained ankle/no rehab and limping for months after the injury cause achilles tightness and bottom of foot pain (metatarsalgia, plantar f)?

Compensation.... Limping for months, with or without pain, can cause a change in the mechanics of your normal walk. This is known as compensatory change or compensation. As the body compensates, you can expect that new problems such as muscle tightness and weight shifting will develop. Treating these new symptoms can be even more challenging than treating the original ones. A Healthtap specialist can help.