England qualified for the World Cup on Saturday but can top their group if they beat Poland in the final qualifying game on Wednesday.
Beckham said: 'I'll speak to Madrid first and see what they want me to do but I'll definitely be here for the game at Old Trafford and I'll be looking after my son as well.'
The previous Saturday Romeo was taken to the public La Paz hospital in Madrid, where he spent two hours before being allowed home.
Then on Wednesday, following an overnight stay in the Ruber Internacional Clinic, the Beckhams flew their son back to Britain on their private jet.
David and Victoria were said to be 'totally distraught' at Romeo's illness and have told friends they fear it is more than just a virus.
Febrile convulsions are common in children up to the age of five and can be caused by the high temperatures which result from infections. But on rare occasions they can be a symptom of more serious problems.
Brooklyn and Cruz also flew to Britain with their grandparents, David's mother Sandra and Victoria's parents Jackie and Tony.
