You need to go have this lump checked out. It's very possible that it's just a nodule, which are very common and most nodules are not cancer, but there's no way you can know that without getting it tested.
Do you know the cause of your hyperthyroidism? Graves Disease is the main cause, but many people with Hashimoto's have hyperthyroidism in the beginning stages, often alternating with hypo or even normal, prior to permanent hypothyroidism. Both Hashimoto's and Graves are autoimmune conditions. If you haven't been tested for them, you should be.
If you can't afford medical treatment, you should check with your county health department and see if you qualify for Medicaid or subsidized health insurance.