The sesamoid bones are two tiny bones at the underside of your big toe, at the joint where it bends between the toes and your foot. These bones are within the flexor tendon of the big toe and they help to disperse the tensions and weight on that joint.
Sometimes these little bones (kind of like a kneecap), and the tendons that they sit it can get inflamed and irritated. It can hurt to walk on them.
The root of the problem can be in the calf. And points to tightening and shortening of the calf, as well as the hamstrings, and the low back. Opening and stretching the whole back of the leg will lengthen the fascia and tendons at the bottom of your foot and help relieve the pain.
These tight toe-flexor tendons are pressing these sesamoid bones into the base of the big toe and it hurts. With the shortening of the big toe flexor tendon, the sesamoids can also migrate out of their shallow grooves, and lay closer to the mid-line of the foot. They would rather ride with the tendon a bit more to the inner side..
The front of the calf is important to release. If these muscular toe extensors are short, you can look down and see if the toe-joint has a bend. This makes the bottom of the big toe is more rounded underneath, and can irritate where the sesamoid bones hit the ground. When you are walking, try pushing off with the tip of your big toe, lightly with each step, to keep the pressure off the ball of that joint.
Manual release of the fascia is effective for this - for the lower leg, as well as through the arch of the bottom of the foot. Releasing the great toe flexor tendon, and gently scooping the sesamoid bones back to the side is standard, as well as mobilization of the ankle, and all mid and fore foot. Adhesive capsulitis can accompany this condition.
Acute care can involve taping the great toe straight - basically lassoing the base of the toe, and carrying taught the tape under the foot, bowstring it across the arch, and taping it down a the back of the heel. The foot cannot bend very well but it can offer some acute relief at home.