7 months after Achilles surgery and bad infections my foot is swollen, painful and hot. Reduced swelling by ice and elevation. Should I be worried?

Achilles Tendon. Achilles tendon surgery is riddled with potential complications for you, as a patient, and for the surgeon. There is very little soft tissue coverage over the tendon, which creates frequent infections and frequent wound dehiscence. Swelling may last for months after surgery. Rehab is essential. Another MRI may be necessary.
Signs of infection. If one's foot is 'swollen, painful and hot, ' consider an on-going infection. Other causes to these symptoms include blood clots and compromised achilles tendon. See your surgeon and request an mri. Don't ignore these symptoms.
Absolutely. You need to go back to your doctor asap and have this fully assessed. If you have not yet seen an infectious diseases specialist you should also do this asap. Do not wait, if this is recurrent or exacerbation of chronic infection and not managed urgently you could be in big trouble. Hope this is better soon.
Have it evaluated. Do not ignore any signs of an infection. Have it evaluated by you surgeon and get their expert opinion.