Trigesteral is a triphasic combined oral contraceptive pill
(OCP). It contains three different combinations of estrogen & progesteron. Generally in asthmatics OCP should be avoided or should be used with caution. Nausea & headache occur in some individuals and is usually transient. But in a smaller fraction of women more severe migraine headaches
can occur. Injections or depot preparations also can result in severe headache
. However if migraine is worse it can increase the risk of cerebrovascular accident & so in such individuals OCP SHOULD BE DISCONTINUED . You are an asthmatic and OCP is consistently resulting in severe headache. So you should stop using OCP & opt for other methods of contraception
like non hormonal copper IUCD.