What does mild increased peribronchial markings on a chest x-ray mean when i was covid positive been having chest pain n short of breath still?

With that history it suggests there is minor evidence of active lung disease but no where near the common intensity seen in covid when it is harsh.

You may have post COVID inflammation and bronchial hyperreactivity. Please discuss the use of an inhaled steroid and possible use of a bronchodilator with your physician. If you experience changes in sleep or exercise ability, further testing may be helpful. The radiograph shows changes which are consistent w the above.