Yes, there are no traditional hernias in the foot. However, if your plantar fascia and other ligaments are weak or injured then pads of fat can slip out and cause lumps. The bones held together by these ligaments may slip from place and cause a lump which looks like hernia. You need to ask your doctor for a MRI. Usually this will be treated conservatively with a cast followed by physiotherapy but you need a definitive diagnosis before treatment is started as the treatment may vary with the type of injury. Hope this helps. Take care!
The medical advice given should not be considered a substitute for medical care provided by a doctor who can examine you. The advice may not be completely correct for you as the doctor cannot examine you and does not know your complete medical history. Hence this reply to your post should only be considered as a guiding line and you must consult your doctor at the earliest for your medical problem.