problem facing when doing nursing diagnosis please help!

when i am doing my assignment, i found that it is hard to desire what diagnosis to be used and their priority, i do not know what rules to use in order to find the best diagnosis and prority in the case, ( severity? the cause? )

i think of impair gas exchange, acute pain and hypertension

as the defination of impair gas exchange is the deficit( or excess , but not in this case) in oxygenation (or carbon dioxide elimination ) at the alveolar-capillary membrane. what i think is the artery is narrowed with the fatty tissue or the clot this make the oxygen cannot deliver to the cell effectively and the symptom seems siutable for this case such as hypoxia(spo2 93%), dyspnea (rr28) tachycardia (Hr110).

acute pain is obvious since that the patient complain of chest pain with pain score 8/10 radiation to the shoulder.

hypertension due to urti

i think oxygen supply is not enough for the patient and it is the cause of mi as well therefore, we should provide oxygen for him asap. am i wrong or there is better solution?

here is my situation,

a man 55 years old, admited to hospital due to severe chest pain and diagnosed with myocardial infraction with history of hypertension, he is conscious and alert on arrival to hospital.

BP 105/79mmHg, Hr 110/min, Temp: 38.2, SpO2 93% (room air) RR 28beats/min Body weight 80kg, height 160cm, pain score 8/10 radiation to shoulder, profuse sweating and cool in extremities.

complain of runny nose, coughs and fever 2 days before and diagnosed with urti, he was coughing and sneezing frequently and refuse to wear surgical mask, he clam he didnt know the importance of wearing surgical mask and didnt know the proper way in wearing the mask, he showed anxious about condition