I speedwalk to/from each of my jobs (cheaper than bus). altogether 8-10mi daily. past 2wks chronic numbness/tingling on tibialis anterior, gets excruciatingly painful & extends to toes when walking. also crackling pain on the muscle when bending down?

Tendinitis: Anterior tibialis is the muscle that is used to lift your toes up when walking, and if you have tight calf muscles, it causes this muscle to work harder. It is considered an overuse problem from xs walking or standing. Cutting back on walking is critical, but ibuprofen, calf stretches, perhaps a shoe with a higher heel, and cold massage may help. You need to r/o stress fracture as well.

Shin splints : Sounds like shin splints, irritation and inflammation of the periosteum (the membrane that surrounds and nourishes the tibia bone). But could also be a stress fracture or exertional compartment syndrome. Try icing it at night and try strengthening the tibialis anterior muscle with dorsiflexion exercises. Physical therapy will help as well. MRI will rule out a stress fracture.