St. John’s wort has quite a few interactions with other medicines:
St. John's wort should only be used carefully with other antidepressants such as MAOIs, SSRIs (e.g. citalopram, fluoxetine, paroxetine, sertraline), tricyclics (e.g. dosulepin, imipramine, lofepramine), duloxetine or venlafaxine.
St. John's wort can sometimes decrease the effect of antiretrovirals (e.g. atazanivir, maraviroc, in dinavir; used to treat HIV), carbamazepine, ciclosporin, digoxin, methadone, omeprazole, oral contraceptives, phenobarbital, phenytoin, tacrolimus, theophylline, verapamil or warfarin.
St. John's wort can increase the effect of some triptans (e.g. sumatriptan, zolmitriptan; for migraine)
It is unwise to stop taking it suddenly, even if you feel better. Your symptoms can return if treatment is stopped too early. This may occur some weeks or even months after St. John’s wort has been stopped. When the time comes, you should withdraw St. John’s wort by a gradual reduction in the dose over several weeks. You should discuss this fully with your doctor, nurse or pharmacist.
Withdrawl symptoms from St. John's Wort include dizziness, confusion, "brain zaps", photosensitivity, headaches, and muscle aches.
Not all of these symptoms happen in everyone but these are the most common.
Do not take 5-hydroxytryptophan without the advice of a healthcare provider if you are using any of the following medications:
dextromethorphan (cough medicine);
St. John's wort;
an antidepressant such as amitriptyline (Elavil, Vanatrip, Limbitrol), citalopram (Celexa), clomipramine (Anafranil), doxepin (Sinequan), fluoxetine (Prozac), imipramine (Tofranil), nortriptyline (Pamelor), paroxetine (Paxil), sertraline (Zoloft), trazodone (Desyrel), and others;
an MAO inhibitor such as isocarboxazid (Marplan), phenelzine (Nardil), rasagiline (Azilect), selegiline (Eldepryl, Emsam), or tranylcypromine (Parnate);
medicine to treat Parkinson's disease, such as carbidopa/levodopa (Atamet, Parcopa, Sinemet); or
prescription pain medication such as meperidine (Demerol), pentazocine (Talwin), or tramadol (Ultram, Ultracet).
5-HTP will cause exactly what you describe when combining it with ultram and when you add St. John's Wort into the mix you have a very bad cocktail that will cause the symptoms you describe.
It can take several weeks for your body to normalize from taking these medications and as a result depression type symptoms may be experienced as well as "brain zaps", anxiety, tremors, confusion, muscle cramps, stomach ailments, weakness, and others.
This is all related to the cocktail and drug interactions in what you were taking. These will also interact with betahistine as well.
Once the mix is out of your system cleared of these medications and your body has time to normalize neurotransmitter levels you should not have the reactions to the ultram or betahistine. This can take several weeks.